package main

import (
	"fmt"
	"log"
	"net/url"
	"path/filepath"
	"strings"
	"time"

	"git.leaktechnologies.dev/stu/VT_Player/player/mpvembed"

	"github.com/gotk3/gotk3/gdk"
	"github.com/gotk3/gotk3/glib"
	"github.com/gotk3/gotk3/gtk"
)

const appCSS = `
* {
    font-family: "Noto Sans", "Cantarell", "Sans";
    color: #E1EEFF;
}
window, GtkDrawingArea, box {
    background-color: #0B0F1A;
}
button {
    background: #171C2A;
    color: #E1EEFF;
    border-radius: 6px;
    padding: 4px 8px;
}
button:hover {
    background: #24314A;
}
label {
    color: #E1EEFF;
}
`

type pane struct {
	area *gtk.DrawingArea
	mpv  *mpvembed.Client
	path string
	id   int
}

func (p *pane) hasVideo() bool { return p.path != "" }

type videoEntry struct {
	id   int
	path string
}

var (
	playlist    []videoEntry
	nextVideoID = 1
)

func main() {
	gtk.Init(nil)

	win, err := gtk.WindowNew(gtk.WINDOW_TOPLEVEL)
	if err != nil {
		log.Fatalf("window: %v", err)
	}
	win.SetTitle("VT Player (GTK/mpv)")
	win.SetDefaultSize(1400, 800)

	grid, _ := gtk.GridNew()
	grid.SetColumnHomogeneous(true)
	grid.SetRowHomogeneous(false)
	win.Add(grid)

	left := newPane()
	right := newPane()

	controls := buildControls(win, left, right)
	grid.Attach(controls, 0, 0, 2, 1)
	grid.Attach(left.area, 0, 1, 1, 1)
	grid.Attach(right.area, 1, 1, 1, 1)

	applyCSS()
	preferDark()

	setupDragDest(left, left, right)
	setupDragDest(right, left, right)

	win.Connect("destroy", func() {
		if left.mpv != nil {
			left.mpv.Destroy()
		}
		if right.mpv != nil {
			right.mpv.Destroy()
		}
		gtk.MainQuit()
	})

	win.ShowAll()
	gtk.Main()
}

func newPane() *pane {
	da, _ := gtk.DrawingAreaNew()
	da.SetHExpand(true)
	da.SetVExpand(true)
	p := &pane{area: da}
	da.Connect("realize", func() {
		var xid uint64
		if w, err := da.GetWindow(); err == nil && w != nil {
			xid = getWindowID(w)
		}

		if p.mpv == nil {
			mpv, err := mpvembed.New()
			if err != nil {
				log.Printf("mpv create: %v", err)
				return
			}
			p.mpv = mpv
			_ = p.mpv.SetOptionString("pause", "yes")
			if xid != 0 {
				_ = p.mpv.SetWID(xid)
			}
			if err := p.mpv.Initialize(); err != nil {
				log.Printf("mpv init: %v", err)
			}
			return
		}

		// mpv already exists (created before realize); make sure WID is bound now
		if xid != 0 {
			_ = p.mpv.SetWID(xid)
		}
	})
	return p
}

func buildControls(win *gtk.Window, left, right *pane) *gtk.Box {
	box, _ := gtk.BoxNew(gtk.ORIENTATION_VERTICAL, 6)
	row1, _ := gtk.BoxNew(gtk.ORIENTATION_HORIZONTAL, 4)
	row2, _ := gtk.BoxNew(gtk.ORIENTATION_HORIZONTAL, 4)

	openL, _ := gtk.ButtonNewWithLabel("Open Left")
	openR, _ := gtk.ButtonNewWithLabel("Open Right")
	play, _ := gtk.ButtonNewWithLabel("Play Both")
	pause, _ := gtk.ButtonNewWithLabel("Pause Both")
	seek0, _ := gtk.ButtonNewWithLabel("Seek 0")
	stepF, _ := gtk.ButtonNewWithLabel("Step +1f")
	stepB, _ := gtk.ButtonNewWithLabel("Step -1f")
	info, _ := gtk.LabelNew("Meta: -")

	openL.Connect("clicked", func() { chooseAndLoad(win, left) })
	openR.Connect("clicked", func() { chooseAndLoad(win, right) })

	play.Connect("clicked", func() {
		if left.mpv != nil {
			_ = left.mpv.SetPropertyBool("pause", false)
		}
		if right.mpv != nil {
			_ = right.mpv.SetPropertyBool("pause", false)
		}
	})
	pause.Connect("clicked", func() {
		if left.mpv != nil {
			_ = left.mpv.SetPropertyBool("pause", true)
		}
		if right.mpv != nil {
			_ = right.mpv.SetPropertyBool("pause", true)
		}
	})
	seek0.Connect("clicked", func() {
		if left.mpv != nil {
			_ = left.mpv.Command("seek", "0", "absolute", "exact")
		}
		if right.mpv != nil {
			_ = right.mpv.Command("seek", "0", "absolute", "exact")
		}
	})
	stepF.Connect("clicked", func() {
		if left.mpv != nil {
			_ = left.mpv.Command("frame-step")
		}
		if right.mpv != nil {
			_ = right.mpv.Command("frame-step")
		}
	})
	stepB.Connect("clicked", func() {
		if left.mpv != nil {
			_ = left.mpv.Command("frame-back-step")
		}
		if right.mpv != nil {
			_ = right.mpv.Command("frame-back-step")
		}
	})

	go func() {
		t := time.NewTicker(500 * time.Millisecond)
		defer t.Stop()
		for range t.C {
			text := metaSummary(left, right)
			_ = glib.IdleAdd(func() {
				defer func() {
					_ = recover()
				}()
				info.SetText(text)
			})
		}
	}()

	row1.PackStart(openL, false, false, 0)
	row1.PackStart(openR, false, false, 0)
	row1.PackStart(play, false, false, 0)
	row1.PackStart(pause, false, false, 0)
	row1.PackStart(seek0, false, false, 0)
	row1.PackStart(stepB, false, false, 0)
	row1.PackStart(stepF, false, false, 0)

	row2.PackStart(info, false, false, 0)

	box.PackStart(row1, false, false, 0)
	box.PackStart(row2, false, false, 0)
	return box
}

func chooseAndLoad(win *gtk.Window, p *pane) {
	dlg, _ := gtk.FileChooserDialogNewWith2Buttons(
		"Open Video",
		win,
		gtk.FILE_CHOOSER_ACTION_OPEN,
		"Cancel", gtk.RESPONSE_CANCEL,
		"Open", gtk.RESPONSE_ACCEPT,
	)
	dlg.SetModal(true)

	// Add file filter for video files
	filter, _ := gtk.FileFilterNew()
	filter.SetName("Video Files")
	filter.AddMimeType("video/*")
	filter.AddPattern("*.mp4")
	filter.AddPattern("*.mkv")
	filter.AddPattern("*.avi")
	filter.AddPattern("*.mov")
	filter.AddPattern("*.webm")
	filter.AddPattern("*.flv")
	filter.AddPattern("*.wmv")
	filter.AddPattern("*.m4v")
	filter.AddPattern("*.mpg")
	filter.AddPattern("*.mpeg")
	dlg.AddFilter(filter)

	// Add "All Files" filter as fallback
	allFilter, _ := gtk.FileFilterNew()
	allFilter.SetName("All Files")
	allFilter.AddPattern("*")
	dlg.AddFilter(allFilter)

	if resp := dlg.Run(); resp == gtk.RESPONSE_ACCEPT {
		filename := dlg.GetFilename()
		if filename != "" {
			log.Printf("Selected file: %s", filename)
			loadIntoPane(p, filename)
		}
	}
	dlg.Destroy()
}

func loadIntoPane(p *pane, filename string) {
	log.Printf("loadIntoPane: filename=%q", filename)
	if !ensurePaneReady(p) {
		log.Printf("loadIntoPane: pane not ready")
		return
	}
	p.path = filename
	p.id = getOrAddVideoID(filename)
	log.Printf("loadIntoPane: calling mpv loadfile command")
	if err := p.mpv.Command("loadfile", filename, "replace"); err != nil {
		log.Printf("loadfile %s: ERROR: %v", filename, err)
	} else {
		log.Printf("loadfile %s: success", filename)
	}
	_ = p.mpv.SetPropertyBool("pause", false)
	log.Printf("loadIntoPane: complete")
}

func metaSummary(a, b *pane) string {
	parts := func(p *pane) string {
		if p == nil || p.mpv == nil || p.path == "" {
			return "[empty]"
		}
		dur, _ := p.mpv.GetPropertyDouble("duration")
		pos, _ := p.mpv.GetPropertyDouble("time-pos")
		w, _ := p.mpv.GetPropertyInt64("width")
		h, _ := p.mpv.GetPropertyInt64("height")
		tag := ""
		if p.id > 0 {
			tag = fmt.Sprintf("#%d ", p.id)
		}
		return fmt.Sprintf("%s%s | %dx%d | %.1f/%.1fs", tag, filepath.Base(p.path), w, h, pos, dur)
	}
	return fmt.Sprintf("L: %s   |   R: %s", parts(a), parts(b))
}

// getWindowID returns the native window handle (XID on X11, HWND on Windows).
func getWindowID(w *gdk.Window) uint64 {
	if w == nil {
		return 0
	}
	// gdk_x11_window_get_xid only works on X11; return 0 on other backends.
	return uint64(gdkWindowGetXID(w))
}

// gdkWindowGetXID extracts the XID from a GDK window when running on X11.
func gdkWindowGetXID(w *gdk.Window) uint {
	return uint(w.GetXID())
}

func applyCSS() {
	provider, err := gtk.CssProviderNew()
	if err != nil {
		return
	}
	if err := provider.LoadFromData(appCSS); err != nil {
		return
	}
	screen, err := gdk.ScreenGetDefault()
	if err != nil {
		return
	}
	gtk.AddProviderForScreen(screen, provider, gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)
}

func preferDark() {
	if settings, err := gtk.SettingsGetDefault(); err == nil && settings != nil {
		_ = settings.SetProperty("gtk-application-prefer-dark-theme", true)
	}
}

func setupDragDest(targetPane *pane, left, right *pane) {
	uriTarget, err := gtk.TargetEntryNew("text/uri-list", gtk.TARGET_OTHER_APP, 0)
	if err != nil {
		return
	}
	targets := []gtk.TargetEntry{*uriTarget}
	targetPane.area.DragDestSet(gtk.DEST_DEFAULT_ALL, targets, gdk.ACTION_COPY)

	targetPane.area.Connect("drag-data-received", func(_ *gtk.DrawingArea, _ *gdk.DragContext, x, y int, data *gtk.SelectionData, _ uint, _ uint32) {
		defer func() {
			if r := recover(); r != nil {
				log.Printf("drag handler panic: %v", r)
			}
		}()
		if data == nil {
			log.Printf("drag-data-received: data is nil")
			return
		}

		log.Printf("drag-data-received: got data")
		uris := parseURIs(data)
		log.Printf("drag-data-received: parsed URIs: %v", uris)
		for _, u := range uris {
			if u == "" {
				continue
			}
			assignPathToPane(u, left, right)
			break
		}
	})
}

// decide which pane to load based on availability: left prefers first, right second.
func assignPathToPane(uri string, left, right *pane) {
	path := uriToPath(uri)
	if path == "" {
		return
	}
	if left != nil && !left.hasVideo() {
		loadIntoPane(left, path)
		return
	}
	if right != nil && !right.hasVideo() {
		loadIntoPane(right, path)
		return
	}
	// default: replace left
	if left != nil {
		loadIntoPane(left, path)
	}
}

func ensurePaneReady(p *pane) bool {
	if p == nil {
		return false
	}
	if p.mpv != nil {
		return true
	}
	mpv, err := mpvembed.New()
	if err != nil {
		log.Printf("mpv create: %v", err)
		return false
	}
	// Bind window if realized
	if w, err := p.area.GetWindow(); err == nil && w != nil {
		if xid := getWindowID(w); xid != 0 {
			_ = mpv.SetWID(xid)
		}
	}
	_ = mpv.SetOptionString("pause", "yes")
	if err := mpv.Initialize(); err != nil {
		log.Printf("mpv init: %v", err)
		return false
	}
	p.mpv = mpv
	return true
}

func uriToPath(u string) string {
	if u == "" {
		return ""
	}
	log.Printf("uriToPath: input=%q", u)

	// text/uri-list format: file:///path
	if strings.HasPrefix(u, "file://") {
		// Use url.Parse to properly handle URL encoding
		parsed, err := url.Parse(u)
		if err != nil {
			log.Printf("uriToPath: url.Parse error: %v", err)
			// Fallback: just strip file://
			u = strings.TrimPrefix(u, "file://")
			// Handle localhost
			u = strings.TrimPrefix(u, "localhost")
			return u
		}
		path := parsed.Path
		log.Printf("uriToPath: parsed path=%q", path)
		return path
	}

	// Not a file:// URI, return as-is
	return u
}

func getOrAddVideoID(path string) int {
	if path == "" {
		return 0
	}
	for _, e := range playlist {
		if e.path == path {
			return e.id
		}
	}
	id := nextVideoID
	nextVideoID++
	playlist = append(playlist, videoEntry{id: id, path: path})
	return id
}

// parseURIs tries to extract URIs from SelectionData while avoiding crashes on bad payloads.
func parseURIs(data *gtk.SelectionData) []string {
	if data == nil {
		return nil
	}

	// try safe path using raw bytes first
	raw := data.GetData()
	if len(raw) == 0 {
		if txt := data.GetText(); txt != "" {
			raw = []byte(txt)
		}
	}
	if len(raw) > 0 {
		var out []string
		for _, ln := range strings.Split(string(raw), "\n") {
			ln = strings.TrimSpace(ln)
			if ln != "" {
				out = append(out, ln)
			}
		}
		if len(out) > 0 {
			return out
		}
	}

	// fallback to GetURIs; guard with recover because upstream may panic on nil C arrays
	defer func() {
		if r := recover(); r != nil {
			log.Printf("GetURIs panic: %v", r)
		}
	}()
	if uris := data.GetURIs(); len(uris) > 0 {
		return uris
	}
	return nil
}